1. Field of the Invention
An embodiment of the invention relates to an image forming apparatus and an image forming system.
2. Description of the Related Art
When printing is performed on the basis of image data of a page description language (PDL) format, the image data of the PDL format is developed into image data of a raster format (hereinafter, referred to as “raster image data”), and printing is performed on the basis of the raster image data. Image forming systems for large-volume printing business, which perform a process at a high speed, often employ a configuration in which a digital front end (DFE) apparatus and an image forming apparatus are separately provided. In the configuration, the EDF apparatus performs a raster image processing (RIP) process of generating raster image data on the basis of image data of a PDL format contained in a print job and the image forming apparatus prints an image on a sheet of paper as a recording medium on the basis of the raster image data. In this case, the DFE apparatus is connected to the image forming apparatus through a network or a high-performance serial bus, and the raster image data that has undergone the RIP process is transferred from the DFE apparatus to the image forming apparatus.
An example of such an image forming system is disclosed in Japanese Patent Application Laid-open No. 2010-99907. In the image forming system disclosed in Japanese Patent Application Laid-open No. 2010-99907, a general mother board for a personal computer (PC) is used as a DFE apparatus, and an image forming apparatus also employs a controller configuration in which a central processing unit (CPU) (processor) used for print control and a local memory are mounted. The raster image data generated by the DFE apparatus is transferred to the image forming apparatus, is then stored in the local memory, and finally supplied to a printer engine.
In the conventional image forming apparatus of the image forming system, a memory which is accessed by the processor for print control and used as a working area and a memory that stores the raster image data transferred from the DFE apparatus are shared on the same bus. However, depending on an operation of software operating on the processor, the processor may continue to preferentially perform memory access. In this case, an operation of writing/reading the raster image data to/from the memory is delayed, and printing performance degrades.